JP2000252597A - Printed-wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent migration without deteriorating the strength of a printed-circuit board even if conductive metal patterns approach each other for a long distance by effectively preventing migration while manufacturing the printed-wiring board simply and easily at low costs and effectively preventing the migration of conductive metal patterns that approach extremely with a potential difference. SOLUTION: In a printed-circuit board, conductive metal patterns 2 are fixed onto the surface of an insulation substrate 1. Further, in the printed-circuit board, a shield metal pattern 3 that is not electrically connected to the conductive metal pattern 2 is provided between the conductive metal patterns 2 that approach each other and have a potential difference. The shield metal pattern 3 shields between the conductive metal patterns 2 with the potential difference, thus preventing short-circuiting due to migration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board that can effectively prevent a short circuit due to migration.

[0002]

2. Description of the Related Art Migration occurs on a printed circuit board when an electrolytic solution adheres thereto. Migration is
Occurs when there is a conductive metal pattern having a potential difference in the electrolyte. The high potential conductive metal pattern in contact with the electrolytic solution is dissolved in the electrolytic solution to become metal ions. The metal ions adhere to and deposit on the low potential conductive metal pattern. When this deposition continues, the metal apparently extends from the low potential conductive metal pattern, reaches the high potential conductive metal pattern, and short-circuits.

This problem can be prevented by increasing the distance between the conductive metal patterns having a potential difference. However, even if the interval is widened, a short circuit caused by migration cannot be solved in principle. For this reason, the period of short-circuit due to migration can be lengthened, but cannot be effectively prevented.

In order to prevent this problem, a technique has been developed in which a slit penetrating a printed board is provided between conductive metal patterns having a potential difference (Japanese Patent Laid-Open No. 10-56).
241). In the printed circuit board of this publication, as shown in FIG. 1, slits 6 are provided between conductive metal patterns 2 having a potential difference. The slit 6 cuts off a path in which the migration grows, thereby preventing a short circuit due to the migration.

[0005]

As shown in FIG. 1, a structure in which a slit 6 is provided between conductive metal patterns 2 having a potential difference to prevent migration increases the manufacturing cost of a printed circuit board. This is because it takes time to open a slit between conductive metal patterns having a potential difference. Furthermore, it is difficult for a printed circuit board having this structure to accurately provide slits between conductive metal patterns that are extremely close together. For this reason, it is difficult to effectively prevent migration that occurs between conductive metal patterns that are very close together. Furthermore, since it is necessary to provide a slit at an accurate position between the conductive metal patterns, it is necessary to process the conductive metal pattern and the slit with extremely high precision, which also increases the manufacturing cost. Furthermore, the printed circuit board shown in FIG. 1 has a disadvantage that when the conductive metal patterns having a potential difference approach each other over a long distance, the slit needs to be long, and the long slit reduces the strength of the printed circuit board.

[0006] The present invention has been developed with a view to solving such a drawback. An important object of the present invention is to provide a printed circuit board which can be manufactured simply and easily at a low cost and which can effectively prevent migration.

Another important object of the present invention is to effectively prevent migration of a conductive metal pattern having a very close potential difference, and to reduce the strength of a printed circuit board even if the conductive metal pattern approaches over a long distance. It is an object of the present invention to provide a printed circuit board that can effectively prevent migration without lowering the image quality.

[0008]

The printed circuit board of the present invention has a conductive metal pattern 2 fixed on the surface of an insulating substrate 1. Between the conductive metal patterns 2 approaching each other and having a potential difference, a blocking metal pattern 3 that is not electrically connected to the conductive metal pattern 2 is provided. The blocking metal pattern 3 blocks between the conductive metal patterns 2 having a potential difference to prevent a short circuit due to migration.

In the printed circuit board according to the second aspect of the present invention, the conductive metal pattern 2 and the shielding metal pattern 3 are made of copper foil adhered to the surface of the insulating substrate 1, and the shielding metal pattern 3 Solder 4 is attached.

According to a third aspect of the present invention, there is provided a printed circuit board comprising: an upper surface of a conductive metal pattern provided on both sides of the shielding metal pattern;
Is covered with the resist 5. Further, the solder 4 attached to the shielding metal pattern 3 is projected from the surface of the resist 5.

A printed circuit board according to a fourth aspect of the present invention is built in a battery pack.

According to a fifth aspect of the present invention, there is provided a printed circuit board according to the present invention, wherein between the conductive metal patterns arranged close to and parallel to each other, an elongated shielding metal pattern extending in parallel with the conductive metal pattern. Is provided.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. However, the following embodiments illustrate a printed circuit board for embodying the technical idea of the present invention, and the present invention does not specify the printed circuit board as follows.

Further, in this specification, in order to make it easier to understand the claims, the numbers corresponding to the members shown in the embodiments will be referred to as “claims” and “ In the column of “means”.
However, the members described in the claims are not limited to the members of the embodiments.

The printed circuit board of the present invention has a structure capable of preventing migration. Migration is
Occurs when the electrolyte adheres to the printed circuit board. In a battery pack including a secondary battery and a printed board on which a charge / discharge control circuit for the secondary battery is mounted, liquid may leak from the secondary battery and adhere to the printed board. Therefore, the printed board of the present invention is particularly effective as a printed board incorporated in a battery pack. Further, the present invention is also effective for a charger for charging by mounting a secondary battery. This is because migration due to the liquid leaking from the secondary battery can be effectively prevented. However, migration occurs when an electrolytic solution other than the liquid leaking from the secondary battery adheres to the printed circuit board. For example,
Water adhering to the surface of the printed circuit board causes migration almost without exception. This is because water other than distilled water contains an electrolyte without exception. Therefore,
The printed circuit board of the present invention is also used as a printed circuit board incorporated in an electronic device other than a battery pack and a charger.

However, as compared with the liquid leaked from the secondary battery, ordinary water adhering to the printed circuit board has a lower concentration of the electrolyte. For this reason, the rate of occurrence of migration is smaller than that of the liquid of the secondary battery. From this, the printed circuit board of the present invention is most suitable for a charger having a high probability that an electrolytic solution having a high concentration of an electrolytic substance adheres.

FIG. 2 is an enlarged plan view of a main part of the printed circuit board. The printed circuit board in this figure has a conductive metal pattern 2 attached to the surface of an insulating substrate 1 close to each other. The insulating substrate 1 is a glass epoxy substrate, a phenol substrate, or the like in which glass fibers are embedded and reinforced. A copper foil is adhered to the surface of the insulating substrate 1. The copper foil is partially removed by etching to provide the conductive metal pattern 2.
The printed circuit board fixes the electronic components and connects the fixed electronic components with the conductive metal pattern 2 to realize an electronic circuit.

Not all of the conductive metal patterns 2 provided on the surface of the printed circuit board have the same potential. In portions where the conductive metal patterns 2 having a potential difference approach each other, as shown in FIG. The blocking metal pattern 3 is disposed between the conductive metal patterns 2 having a potential difference so as not to be electrically connected to the conductive metal pattern 2. The shielding metal pattern 3 is a conductive metal pattern 2
In the same manner as described above, the copper foil adhering to the surface of the insulating substrate 1 is provided by etching. The shielding metal pattern 3 is provided to prevent a short circuit due to migration of the conductive metal pattern 2 disposed on both sides. Therefore, the shielding metal pattern 3 is provided between the conductive metal patterns 2 having a potential difference.

In the printed circuit board shown in FIG. 1, conductive metal patterns 2 having a potential difference are arranged close to and parallel to each other. The shielding metal pattern 3 extends in parallel with the conductive metal pattern 2 and is disposed in the middle between the two conductive metal patterns 2. As shown in FIG. 2, the shielding metal pattern 3 is preferably provided so as to extend to a length where both ends protrude from a portion where the conductive metal patterns 2 having a potential difference approach each other. This is for surely shutting off between the conductive metal patterns 2 approaching each other and effectively preventing a short circuit due to migration.

Further, in the printed circuit board shown in FIG. 3, solder 4 is attached to the shielding metal pattern 3 so that the shielding metal pattern 3 is thicker than the conductive metal pattern 2. The solder 4 is attached to the surface of the shielding metal pattern 3 after the conductive metal pattern 2 and the shielding metal pattern 3 are provided by etching the copper foil on the surface of the insulating substrate 1. In order to attach the solder 4 to the shielding metal pattern 3, a portion where the solder 4 is not attached is covered with a resist 5. The resist 5 is an insulating film that covers the surface of the printed board.

The resist 5 has a portion excluding the top of the blocking metal pattern 3, that is, the upper surface of the conductive metal pattern 2 disposed on both sides of the blocking metal pattern 3, the blocking metal pattern 3 and the conductive metal pattern 3. 2 are attached to the area including The resist 5 prevents the solder 4 from adhering to the surface of the printed circuit board. Therefore, the solder 4 is attached to the upper surface of the shielding metal pattern 3 without the resist 5. The solder 4 attached to the shielding metal pattern 3 is provided so as to protrude from the resist 5 as shown in the sectional view of FIG.

As shown in FIG. 3, a resist 5 is adhered between the conductive metal patterns 2 having a potential difference, and solder is applied on the shielding metal pattern 3 provided therebetween so as to protrude from the resist 5. The printed circuit board provided with 4 can extremely effectively prevent a short circuit due to migration. That is, the metal pattern 3 blocks the electrolytic solution adhering between the conductive metal patterns 2 having a potential difference,
This is because a state where the conductive metal pattern 2 does not contact can be realized.

[0023]

The printed circuit board of the present invention has a feature that it can be manufactured simply and easily at a low cost and migration can be effectively prevented. This is because the printed circuit board of the present invention is provided with a shielding metal pattern that is not electrically connected to the conductive metal pattern between the conductive metal patterns approaching each other and having a potential difference. In the printed circuit board having this structure, since the blocking metal pattern that is not electrically connected to the conductive metal pattern blocks between the conductive metal patterns having a potential difference, migration occurring between the conductive metal patterns can be effectively prevented. . Therefore, the printed circuit board of the present invention can realize the feature that even if it is a conductive metal pattern having a very close potential difference, it can be easily and easily manufactured at a low cost, and a short circuit due to migration can be effectively prevented.

Further, the printed circuit board of the present invention can prevent a short circuit due to migration of the conductive metal pattern without providing a slit between the conductive metal patterns having a potential difference as in the prior art. There is a feature that the migration can be effectively prevented without lowering the strength of the printed circuit board even when approaching.

[Brief description of the drawings]

FIG. 1 is a plan view of a conventional printed circuit board.

FIG. 2 is a plan view of a printed circuit board according to an embodiment of the present invention.

FIG. 3 is a sectional view of a printed circuit board according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating board 2 ... Conductive metal pattern 3 ... Blocking metal pattern 4 ... Solder 5 ... Resist 6 ... Slit

Claims (5)

[Claims] 1. A conductive metal pattern on a surface of an insulating substrate (1).
In the printed circuit board on which (2) is fixed, the conductive metal pattern (2) is located between the conductive metal patterns (2) approaching each other and having a potential difference.
A printed circuit board provided with a shielding metal pattern (3) that is not electrically connected to the printed circuit board. 2. The conductive metal pattern (2) and the shielding metal pattern (3) are copper foil adhered to the surface of the insulating substrate (1), and the solder (4) is placed on the shielding metal pattern (3). Claim 1 which has adhered
Printed circuit board described in. 3. An upper surface of a conductive metal pattern (2) disposed on both sides of the shielding metal pattern (3), and an upper surface of the shielding metal pattern.
Resist the area including between (3) and the conductive metal pattern (2).
The printed circuit board according to claim 2, wherein the solder (4) coated with (5) and attached to the shielding metal pattern (3) projects from the resist (5) to the surface. 4. The printed circuit board according to claim 1, wherein the printed circuit board is a printed circuit board built in a battery pack. 5. A shielding metal pattern (3) extending parallel to the conductive metal pattern (2) between the conductive metal patterns (2) arranged close to and parallel to each other. 2. The printed circuit board according to 1.